Biomedical subjects

F Rueggeberg

Publications and source records attributed to F Rueggeberg.

5 recordsLinked to original sources

PubMed1999

New light curing options for composite resin restorations.

The concerned practitioner needs to understand the chemistry of the materials, the dynamics of polymerization, the stress factors created, and the specific light energy requirements needed to attain maximum results. If a practitioner chooses to use one of the nontraditional curing systems, he or she needs to consult with the manufacturer to determine the spectral output of the system, and contact the manufacturer of the composite to ensure that the material used will cure properly with the chosen light source. The manufacturers have customer service representatives who are usually very knowledgeable about their products. Current claims about new technological developments based on laboratory experiments and anecdotal information are promising. However, multicenter prospective clinical studies are still needed to validate safety and efficacy. Then clinicians can make informed decisions that will enable them to provide the highest quality dentistry for their patients. We will revisit this topic as more information becomes available.

Argon↗

PubMed1999

Contemporary issues in photocuring.

Currently, there is much confusion regarding differences among the variety of light-curing units on the market. Units range from conventional, fixed, continuous output quartz-tungsten-halogen (QTH) models, to very high-intensity systems such as the plasma-arc (PAC) units and the argon-ion lasers. Also, a trend has been established for purposefully providing low light intensity output during initial phases of the curing exposure: the so-called "soft-start" method. Proponents of this method state that by decreasing the rate at which a photoactivated resin cures, stress buildup at the tooth/restoration interface can be minimized, resulting in enhanced marginal integrity.

Composite Resins↗

PubMed1995

Resin cure determination by polymerization shrinkage.

OBJECTIVES: This study was designed to develop a methodology that would measure the monomer conversion of dental restorative resins without the use of an infrared spectrometer. METHODS: Specimens were prepared from heat-cured TEGDMA/MMA copolymers consisting of 0, 20, 40, 50, 80, and 100 mol% TEGDMA. The pre- and post-cure volumes of bar-shaped specimens (45 X 7 X 1 mm) and thin films were measured. The cure of the thin specimens was determined using changes in resin volume as well as by an infrared spectroscopic method. The cure of thin specimens of a commercially available unfilled bonding resin was also determined using the shrinkage method and by conventional infrared spectroscopic methods. RESULTS: There was no difference (p=0.0617) between cure values of the commercial resin using either conventional IR methods or the shrinkage methods. For each copolymer combination of thin films, there was also no significant difference in the extent of cure between the IR method used and the shrinkage method presented (lowest p-value 9.29). The cure of TEGDMA/MMA copolymer bar specimens demonstrated a decreasing trend of cure with increasing proportion of TEGDMA, and had cure values which were similar to others reported in the literature. SIGNIFICANCE: The evidence from this study demonstrated that the specimen volume method can be used to determine the extent of resin cure of thin film or bulk resin specimens. This method represents an easily performed procedure that can be used by all investigators without expensive equipment.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1991

Correlation of cytotoxicity, filler loading and curing time of dental composites.

Previous studies have shown that dental resin composites tested in cell culture produce cytotoxic effects on human gingival tissues. In this study, the cytotoxic potential of resin composites on primary human gingival fibroblast cultures was evaluated, based on inhibition of cellular protein synthesis measured by [35S] methionine incorporation. Both resin content and percentage of monomer conversion were considered as potential causes of cytotoxicity. Three resin composites were selected to provide a range of filler content from 45 to 86 wt%. Duplicate sample discs (1 mm thick x 10 mm diameter) of each composite were polymerized for 15, 30 and 60 s, followed by heat (110 degrees C, 10 min), and the degree of monomer conversion for each sample group was measured using Fourier transform infrared spectrophotometry. Identically fabricated discs were placed into 35 mm culture dishes with gingival fibroblasts and incubated for 24 h at 37 degrees C. The cell monolayers then were labelled at 24 h with [35S] methionine, washed and solubilized; then incorporated radioactivity was quantitated by liquid scintillation spectrometry. For each composite, as the percentage of monomer conversion increased, cellular toxicity decreased. In comparing different composites having similar monomer conversions, it was found that the filler/resin ratio was not the only factor determining the composite's relative toxicity.

Biocompatible Materials↗

PubMedDate not supplied

Cariostatic and ultraconservative sealed restorations: nine-year results among children and adults.

The objective of this clinical study was to evaluate the long-term efficacy of placing sealed posterior composite restorations for arresting active caries. The tooth preparation for this bonded and sealed restoration was limited to placing a bevel in the enamel only, without the removal of the carious lesion. The radiographic and clinical performance of these ultraconservative sealed composite restorations placed over caries (CompS/C) was compared over a period of nine years with: 1) ultraconservative, localized sealed amalgam (AGS) restorations with no extension for prevention, and 2) traditional, unsealed amalgam restorations (AGU) with the usual extension for prevention outline form. Sealant retention with > 50 percent to 100 percent of the margins occurred in 64 percent of CompS/C and 82.5 percent of AGS restorations. After nine years the cumulative failure rates were 16 percent for CompS/C, 2.5 percent for AGS, and 17.1 percent for AGU restorations. Thus, the clinical performance of CompS/C restorations was slightly superior to that of the traditional AGU restorations. The AGS restorations were definitely superior to the traditional AGU restorations and to the CompS/C restorations in both children and adults alike. Complete sealant retention over CompS/C and AGS restorations was equivalent between children and adults (P = 0.14 and 0.74, respectively). A higher percentage of open margins in CompS/C restorations was seen, however, in children (17.4 percent) than adults (1.94 percent). This study has shown that Class I caries can be arrested by the CompS/C restoration.

Adolescent↗